Safety timer



F. A. PURDY SAFETY TIMER 3 Sheets-Sheet 1 Filed Sept. 26, 1968 11! .Il L

INVENTOR FQEOffi/CAA. PM? y ATTORNEYS May 12, 1970 F. A. PURDY 3,510,982

. SAFETY TIMER I Fileyd Sept. 26,, 1968 3 Sheets sheet 2 ATTORNEYS F. A. PUR DY SAFETY TIMER May 12, 1970 3 Sheets-Sheet 5 Filed Sept. 26, 1968 ATTORNEYS United States Patent U.S. Cl. 49-30 10 Claims ABSTRACT OF THE DISCLOSURE A safety timer for a motor operated door in which the motor for opening and closing the door is connected to an electrical circuit having means for reversing the motor, the safety timer including a tube having a first and second chamber, a conductive granular material in the tube, a pair of electrical conductors in the tube and connected to the electrical circuit of the door motor and means on the door for positioning one of the chambers of the safety timer tube above the other so that the granular material in the tube will flow by gravity from one chamber to the other.

This invention relates to a door operator and, more particularly, to a safety timer for a door operator, actuated from the headlights of a vehicle, for preventing inadvertent operation of the door.

Door operators, responsive to the headlight beam of a vehicle, for opening and closing garage doors, have been known for some time, such as the door operator shown and described in my co-pending application Ser. No. 401,- 264, filed Oct. 2, 1964, now Pat. No. 3,444,344, and in my patents and applications referred to therein. In such operators, the door is connected to a motor, usually by an endless cable and pulleys or by a shaft threaded the length of the door-drive into a nut or pinion on a carriage that moves with the door, and the motor is controlled by a relay, a reversing switch, and a light sensitive cell. Usually, in such a system, the cell is shielded so that light of the headlamp beam of the vehicle can reach the light sensitive element of the cell but light from other sources, such as ambient light, is prevented from reaching the light sensitive element in the housing, by baffle, by filters or the like. In any event, when exposed to the headlight beam of an approaching vehicle, the door-drive motor is actuated to open or close the door.

Once the light sensitive element of the cell of such a door operator has been exposed to the headlight beam of an approaching vehicle, in the prescribed manner, initiating actuation of the door, the motor continues to operate until the door is opened or closed. When the door reaches its fully opened or fully closed position, the mo tor is reversed so that, when again exposed to a headlight beam, the motor will actuate the door in the reverse direction. While the motor is opening or closing the door, the power-switch in the circuit to the motor has taken over, unaffected by any exposure of the light sensitive element of the cell.

Before the vehicle can enter, or leave, the garage, the door must be in, or near to, its fully opened position.

The driver of the vehicle approaching the garage directs the headlight beam of the vehicle toward the light sensitive cell for a prescribed time interval, not greater than two or three seconds, then turns the lights off for motor-actuation by extinguishment as described under operation in the aforementioned application, Ser. No. 401,- 264. The garage door motor, when the door reaches the fully open position, will stop and reverse, leaving the door open with the door operator motor reversed to close the door when the motor control circuit is again actuated. If, however, the driver of the vehicle, after activating the ice motor with the headlight beam to open the door, waits with headlights extinguished until the door is fully open before proceeding into the garage and, before proceeding, turns on the headlights, the headlight beam, applied and withdrawn by movement of the car, may reactivate the motor and cause the door to close on the vehicle as it is being driven into the garage. Even if the headlights on the vehicle entering the garage are not turned on, until the light-beam is moved clear of the light sensitive cell, the light sensitive cell on the door frame might be actuated, accidentally, by the headlight beam of another vehicle, causing the door to close on the first vehicle as it is passing through the garage doorway. In either event, if the door starts to close while the first vehicle is in the doorway, damage to the vehicle and the door may result.

In the instant invention, the door motor is inoperative for a predetermined period of time after the door opens thereby preventing inadvertent, or accidental, operation of the door and resulting damage to the door and vehicle. This is accomplished, in the instant invention, by a twochambered hour-glass type of switch having electrical contacts and containing electrically conductive granules by which a low amperage circuit transformerto cell-to relay-coil, is opened when the door reaches fully open position, and is mechanically closed when, through a safety period, gravitational drainage from one chamber builds up in the other chamber a sufiicient pack of granules to surround the electrical contacts imbedded in the hourglass to effect a reclosing of the circuit in its wiring between cell and relay-coil. In one embodiment, the timer is effective so that the door motor is inoperative after the door is opened and, in another embodiment, after the door is opened and also after the door is closed.

The invention will be better understood from the following description of preferred embodiments of the invention and the drawings in which:

FIG. 1 is a side elevational view of the door operator with a schematic view of the door operator control circuit and showing the operator with the door is closed position with a vehicle in position to activate the door;

FIG. 2 is an enlarged view, in greater detail, of the door operator of FIG. 1, with the door in open position and with the cover of the motor control cabinet broken away;

FIG. 3 is a further enlarged view of portions of the door operator of FIG. 2 showing the timer switch in position before and in phantom line after timer movement;

FIG. 4 is an end view of the operator of FIG. 2;

FIG. 5 is a view taken along line 55 of FIG. 3;

FIG. 6 is a view taken along line 66 of FIG. 3; and

FIG. 7 is a view, partly in section, of a modified timer of the instant invention.

Referring to FIGS. 1 and 2, door 2 is a conventional overhead door, guided and supported by a roller 8 in a track 4 that is mounted on garage wall 6. Door 2 is counter-balanced in conventional manner by spring 10, connected to door 2 by cable 12, passing around a pulley 14 that is mounted on garage wall 6. Roller 8 is connected by links 16, 18, 20, 22, 24 and rollers 26, 28, 30, 32, to roller 34, all in track 4, and roller 34 is, in turn, con- 'nected by pin 36 to plate 38. Plate 38 is held in position on pin 36 by cotter key 40 having, at its end, ring 42 for manually removing cotter key 40 and releasing plate 38 from pin 36, in case of power failure, so that door 2 may be opened and closed manually, in conventional manner. Cable 44 is looped through opposite ends of plate 38 and angularly above pin 36, to clear pin 36 for free removal of plate 38. The looping of cable 44 through plate 38 looks cable 44 to plate 38, to roller 34, and to the door through links 16-24 and bracket 8. Thus, as cable 44 is moved in alternately opposite directions, door 2 is raised or lowered.

The ends of cable 44 are interconnected by turn-buckle 50 forming an endless cable loop around a pulley 52 that is mounted on garage-wall 6, thence leftward of FIGS. 1 and 2 to sheave 54 which is slidably held and springpressed for a frictional drive upon cable 44. Sheave 54 is fitted by a flat to a fiat on shaft 56 of reversible motor 58, the motor body not being shown in the mechanical arrangement in FIG. 1 but shown diagrammatically in the circuit diagram in FIG. 1.

Referring now to FIG. 2, motor 58 with base-flanges upward is held by bolts 57 and 59 under an upper horizontal flange of suspender 60. The main web of suspender 60 reaches down to its lower flange (horizontal) to take bolts such as 61' through top of cabinet-housing thus supporting the cabinet. Shaft 56 entirely supported by bearings in motor 58, extends rearward through an aperture in suspender 60. Vertical and horizontal ends of the leftward extremity of track 4 are butted against the rightward extreme edges, vertical and horizontal, of suspender 60. The butted contact of track 4 and suspender 60" is held rigid by bolts to a saddle 61 of right angle section on top of each, and back of each, as outlined in broken lines, FIG. 2. Shifters 62, 64, are pivotally mounted, respectively, on suspender 60 by pins 66, 68 fixed to suspender 60, and are interconnected, at their lower ends, by connector 70. Spring 72 is connected, at one of its ends, to

one end of connector 70 and, at its other end, spring 72 is connected to rocker 74. Spring 76 is connected, at one of its ends, to the opposite end of connector 70 and, at its other end, spring 76 is connected to rocker 74. Rocker 74 is pivotally connected, intermediate its ends, by pin 78 to bracket 80 which is riveted to suspender 60. Control plate 92 is connected, at its upper end, by pin 94, held in place by cotter pin 96, to one end of rocker 74 and is moved upward and downward in cabinet housing 90 by rocker 74 as door 2 reaches its closed and opened positions.

Referring now to FIGS. 3, 4 and 5, timer tube 100 of electrically non-conductive material, such as glass or plastic, is closed at its opposite ends by caps 102, 104, and is held at its two ends to cradle 106. Cradle 106 is pivotally mounted, off center of timer tube 100, on a round rod 110, one end of which is supported on a stanchion 91 and the farther end in cabinet-housing 90. Cradle 106 is held to shaft 110 by pins 112, 112' extending through rod 110 either side of cradle 106.

Timer tube 100 is partially filled with an electrically conductive material, such as lead pellets, metal shot, mixture of lead pellets with silver powder, or combinations thereof, and is divided, intermediate its ends, into two compartments by divider 114, having a metered opening 116 passing therethrough and interconnecting the two chambers of timer tube 100. As shown in FIGS. 3 and 7 the electrically conductive material in timer tube 100 fills one chamber and the lower end of the other chamber, the upper end of the chamber in both figures being empty.

In the embodiment of the invention shown in FIG. 3, spaced conductors 120, 122, connected to electrical leads 124, 126, respectively, are both located in one of the timer chambers. In the embodiment shown in FIG. 7, one of the conductors 120', connected to lead 124', is located in one chamber and the other conductor 122', connected to lead 126', is located in the other chamber. The significance of this difference in the embodiments will be explained later.

With particular reference to FIGS. 3, 4 and 5, in addition to the pivotal mounting of cradle 106 on rod 110, cradle 106 is connected, by control-link 130, to control plate 92, control link 130 being pivotally connected by pin 132 at the upper of its ends to control plate 92 and, at its lower end, by pin 134 to cradle 106.

As best shown in FIG. 4, timer tube 100, cradle 106, control link 130 and the various parts associated therewith are all located at the leftward side of control plate 92. At the opposite side of control plate 92, solenoid 140, having a plunger 142, is fixed to cabinet housing 90. The

outer end of solenoid plunger 142 is connected to pitman 144, which in turn is connected to the upper end of actuator 146, all more particularly described, with the interconnection and operation thereof, with reverser contacts 152, 154 in my aforementioned co-pending application Ser. No. 401,264 referred to hereinabove.

In the operation of the door operator of the instant invention, the light beam from headlight 200 of a vehicle 202 approaching the garage door 2, which is in closed position, with the headlights turned on, strikes light sensitive cell 204, lowering the electrical resistance of the cell, causing an increase of current to pass through cell 204 from the secondary winding of transformer 206. Garage door 2 has been closed for some time before vehicle 202 approaches the door with its headlights turned on and contacts 120, 122 in timer 100 are closed by the electrically conductive granules or pellets in timer tube 100. The passage of current through the secondary winding of transformer 206 energizes the coil of relay 208 to close relay switch 210 of relay 208 and energize motor 58 in the manner described in. greater detail in aforementioned co-pending application Ser. No. 401,264, it being sufiicient for the instant invention that, when the light beam from headlight 200 of vehicle 202 illuminates cell 204, and is promptly withdrawn from cell 204, motor 5'8 is energized to open the door.

With motor 58 energized, motor 58 turns sheave 54 in a counter-clockwise direction, as viewed in FIG. 1, moving button 44a, locked on cable 44, away from shifter 64 and moving button 44b, locked on cable 44, toward shifter 64. Motor 58 continues to turn sheave 54 in the counterclockwise direction until door 2 is fully open. Shifters 62, 64, interconnected by connector 70, are in the position shown in FIG. 1 as motor 58 starts to open door 2, i.e., shifters 62, 64 are canted in the clockwise direction about pins 66, 68, respectively.

As door 2 approaches its fully opened position, button 44b on cable 44 contacts the upper end of shifter 64 and, as motor 58 continues to turn sheave 54 counter-clockwise, pivots. shifters 64, 62 in a counter-clockwise direction around pins 68, 6-6. As shifters 64, 62 are pivoted counter-clockwise, spring 72, connected at one of its ends to connector 70 and at its other end to rocker 74, pivots rocker 74 clockwise around pin 78, lowering control plate 92 in cabinet housing which, in turn, rotates timer clockwise about shaft as viewed in FIGS. 1, 2 and 3, so that elevated end of timer 100, shown in full line position in FIG. 3, is pivoted clockwise and downward in the direction of the arrow in FIG. 3 until timer 100 is in the phantom line position of FIG. 3. As timer 100 is pivoted from the full line to the phantom line position in FIG. 3, the conductive granules or pellets in timer 100 flow from one chamber to the other, temporarily opening the circuit in timer 100 between conductors 120, 122 and temporarily opening the circuit between light sensitive cell 204 and the secondary winding of transformer 206 and coil of relay 208. The circuit remains open until sufficient of the granules or pellets have passed through metered opening 116 in divider 114 to re-establish current flow between conductors 120, 122. While conductors 120, 122 remain open the application of light to light sensitive cell 204 can not activate transformer 206 and relay 208, relay switch 210. Thus, while conductors 120, 122 remain open, the door 2 which, when it reaches its fully open position reverses motor 58, as described in my aforementioned 401,264 application, can not be closed by application of light to cell 204 or by closing manual switch 230 on the frame of the door opening. This assures that, during the time interval that contacts 120, 122 are open, door 2 can not be inadvertently operated to close onto the vehicle as it is entering the garage. By choice of size of metered opening 116 and the size of the granules or pellets in timer 100, the time interval during which timer 100 maintains the circuit open can be regulated.

In the embodiment of FIG. 3, both conductors 120, 122 are in the same chamber and, as door 2 moves into the full open position and timer 100 is pivoted into the phantom position of FIG. 3 the circuit between conductors 120, 122 is temporarily opened because the granules that have been in position to conduct current between conductors 120 and 122 immediately fall away from the conductors and drop down onto cap 102. Whereupon the drifting begins through the metered hole 116 and continues for a safety-time-period until the fill of granules mounts to embrace both conductors and thus to close the circuit.

A lifting at closing of door to return timer 100' in direction the reverse of the arrow and into the full-line position of FIG. 3 does not open the circuit for the reason that the already full chamber continues with granules packed high above and around the conductors and, though granules drift through the metered hole, the drift stops while still a surplus of granules embraces the conductors, prevented from drifting into a then filled lower chamber. Thus; in the FIG. 3 embodiment, the circuit between conductors 120, 122 although opened, as described, when timer 100 is pivoted downward as the door reaches the open position, are not opened when timer 100 is pivoted upward as the door reaches the closed position.

In the embodiment of FIG. 7, timer tube 100' is shown as having conductor 120' above divider 114' and conductor 122' below divider 114'. This provides two safety periods, one period, the more essential for safety, after the door has been brought into open position, the other, useful though less essential (as when an automobile having passed out of the garage is being maneuvered in the driveway), after the door has been brought into closed position, the position of FIG. 7.

In this embodiment, upon either chamber being brought into a downward position the small over-plus of granules that appears in FIG. 7 above the conductor (as 120') immediately falls away from the conductor and down onto the end-cap (as 102') leaving the conductor bare and thus opening the circuit and holding it open for a safety time period awaiting the build-up of granules from the upward chamber through aperture 116' to reach and surround the conductor in the lower chamber, while an overplus of granules remains in the upper chamber to hold the closed circuit complete.

Conductors as in FIG. 7 are more widely separated than in the first embodiment of FIG. 3. Distance of travel is an obstacle in gaining dependability of current flow through light-weight granules especially when the amperage is at a low ebb such as 4 to 6 milliamperes, having made its way through a light sensitive cell. A further impediment to current-flow is the breadth of the opening 116' in divider 114', this opening being restricted to afford an adequate time-period. Silver has the greatest conductivity of available metals, rating 104 relative to copper at 100, and relative to lead at 7.71. Cost to supply a timer-tube with silver is an obstacle, and silver becomes a defense priority-item in war-times. But silver-dust is a scrap-item obtainable at $25 per pound at peace-times. A small amount of silver-dust mixed into lead-granules is something of a discovery. It provides hundreds of paths for low amperage current to flow relatively considerable distances through a restricted aperture in an electrically insulating disc such as divider 112. Silver powder, alone cakes at a small drift-hole as would wheat flour. Silverpowder in the mixture with lead-pellets affords conductivity, while lead-pellets draw the mixture through a small drift-hole for maintaining the timer-flow.

The terms and expressions which have been employed are used as terms of description and not of limitation, and there is no intention in the use of such terms and expressions of excluding any equivalents of the features shown and described or portions thereof, but it is recognized that various modifications are possible within the scope of the invention claimed.

What is claimed is:

1. A safety timer for a motor operated door in which said motor is connected to an electrical circuit, said electrical circuit having means for reversing said motor when said door is driven by said motor to an opened and a closed position, said safety timer including means connected to said door for moving said safety timer into a first position as said door reaches its open position and into a second position as said door reaches its closed position, said safety timer including means connected to said circuit for opening said circuit to said motor when said timer is moved from one of said positions to the other of said positions and means in said timer for closing said circuit at a predetermined time interval after said timer opens said circuit.

2. A safety timer as recited in claim 1 in which said safety timer includes a tube having a first and a second chamber, a metered opening between said chambers and an electrically conductive granular material in said chambers, said granular material flowing from one of said chambers to the other of said chambers when said timer is moved into said first position and from said other of said chambers to said one of said chambers when said timer is moved into said second position.

3. A safety timer as recited in claim 2 in which said timer includes spaced electrical contacts which, when said timer is moved from said first position to said second position, are open and after said predetermined time interval are closed by said conductive granular material which, during said predetermined time interval flows from one of said chambers to the other of said chambers.

4. A safety timer as recited in claim 3 in which said spaced electrical contacts are in one of said chambers.

5. A safety timer as recited in claim 3 in which one of said spaced electrical contacts is in one of said chambers and the other of said spaced contacts is in the other of said chambers.

6. A safety timer for a motor operated door in which said motor is connected to an electrical circuit, said electrical circuit having means for reversing said motor when said door is driven by said motor to an open and a closed position, said safety timer including means connected to said door for moving said safety timer into a first position as said door reaches its open position and into a second position as said door reaches its closed position, said safety timer including a shell of non-electrically conductive material, said shell having a first chamber and a second chamber interconnected by a restricted, electrically insulated passageway, an electrically-conductive fiowable material in said shell flowable from one of said chambers to the other of said chambers through said restricted, electrically insulated passageway when one of said chambers is positioned above the other of said chambers, relay means in said electrical circuit connected to said motor for opening and closing said circuit to said motor, a relay control circuit connected to said relay, means in said relay control circuit for opening and closing said relay, spaced electrical conductors in said relay control circuit, said conductors passing through said shell of non-electrically conductive material in at least one of said safety timer chambers and being exposed in said chambers in said safety timer to said electrically-conductive fiowable material, said means connecting said safety timer to said door including means for positioning one of said chambers above the other of said chambers, so that said fiowable material will flow by gravity from said one chamber to said other chamber.

7. A safety timer as recited in claim 6 in which said fiowable material in flowing by gravity from said one chamber to said other chamber opens the circuit between said conductors in said relay control circuit, said circuit between said conductors remaining Open until suflicient of 7 said fiowable material has flowed through said insulated passageway from said one of said chambers to said other of said chambers and re-closes said circuit between said conductors.

8. A safety timer as recited in claim 7 in which said 5 flowable material is metal granules.

9. A safety timer as recited in claim 8 in which said metal granules are lead pellets.

10. A safety timer as recited in claim 9 in which said lead pellets are mixed with silver dust.

8/1962 Purdy 49-25 X 10/1962 Purdy 318266 I. KARL BELL, Primary Examiner US. Cl. X.R. 

